Temperature Change Unit

Temperature change, that can be increase or decrease, is defined as the difference between final temperature and initial temperature. Hence, we have different rules when we deal with converting temperature change unit from them with only converting the temperature unit. To illustrate, an object which the initial temperature is 25°C is heated. After a minute, its temperature become 30°C. Our task is to find the temperature change in Fahrenheit unit.

Notice that we would have had a different result if we changed the way like the step below :
1. At first, substract the final temperature by the initial temperature.
30°C – 25°C = 5°C
2. Convert the result from step 1 into Fahrenheit unit. If you think it is the answer, IT IS WRONG.
5°C = (5/5 x 9 + 32) °F = 41°F

Once again, look at step 2 from the wrong way. If we don’t add 32 (just 5/5 x 9), we will have the right answer (9°F). In brief, when we deal with converting temperature change unit, we just look the ratio of each unit.
Celcius : Fahrenheit : Reamur : Kelvin = 5 : 9 : 4 : 5